Polyalkylene glycol mercaptosuccinimides dispersants for lubricant fluids

ABSTRACT

A NEW CLASS OF COMPOUNDS AND A SERIES OF NOVEL LUBRICANT COMPOSITIONS ARE DISCLOSED. POLYALKYLENE GLYCAL MERCAPTOSUCCINIMIDES WHICH ARE USEFUL AS DISPERSANTS IN POLYALKYLENE GLYCAL LUBRICANT FLUIDS AS SLUDGE DISPERSANTS AND LUBRICANT FLUID COMPOSITION INCLUDING SUCH MERCAPTOSURCINIMIDES ARE DESCRIBED.

United States Patent Oflice 3,706,763 Patented Dec. 19, 1972 US. Cl. 260--326.5 S 7 Claims ABSTRACT OF THE DISCLOSURE A new class of compounds and a series of novel lubricant compositions are disclosed. Polyalkylene glycol mercaptosuccinimides which are useful as dispersants in polyalkylene glycol lubricant fluids as sludge dispersants and lubricant fluid compositions including such mercaptosuccinimides are described.

RELATED APPLICATIONS This application is a divisional application of US. patent application Ser. No. 765,994, filed Oct. 8, 1968, now Pat. No. 3,598,735.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to chemical compositions and, more particularly, to chemical compositions useful as lubricating fluid additives and to lubricating fluid compositions. Still more particularly, this invention relates to polyalkylene glycol mercaptosuccinimide lubricant additives and lubricant compounds.

Description of the prior art Motor fuel lubricants, such as conventional automobile motor oil or oils designed for special applications, e.g., marine, aircraft and stationary engines, conventionally include oxidation inhibitors and dispersant additives. Viscosity improvers, etc. are also conventionally added to the basic lubricant fluid to provide particular characteristics desired in the end lubricating compound.

Large classes of hydrocarbon-based or hydrocarboncontaining additives are commercially available for use in conventional hydrocarbon lubricating fluids. It is, of course, essential that any successful additive be soluble -in the lubricating fluid at all potential operating or handling conditions. Long chain aliphatic hydrocarbon substituted succinic acid-amine derivatives have been proposed as dispersant additives for hydrocarbon-based lubricant fluids, see U.S. Pat. No. 3,172,892, LeSuer and Norman, for example.

A new class of potentially commercially valuable lubrieating fluids has been developed, however, in which most known dispersant additives are insoluble or of limited solubility. It is, accordingly, an object of this invention to provide improved dispersant additives for non-hydrocarbon lubricant fluids.

SUMMARY OF THE INVENTION A new class of synthetic crankcase oils for use in automobile engines, aircraft engines, marine engines, stationary engines and the like, are described. The basic fluid, in the preferred embodiment, is a polypropylene glycol diether polymer identified hereinafter as Ucon fluid DLB-200E. It has been found that while many oxidation inhibitors useful in petroleum derived hydrocarbon lubricant fluids may be used with the synthetic crankcase oils of this invention, none of the dispersant additives previously known are sufliciently soluble and are otherwise successful as dispersants in the synthetic crankcase oil compositions of this invention. It is, accordingly, a principal object of this invention to provide a new and improved dispersant additive for use in propylene glycol diether polymer synthetic lubricating fluids.

Similarly, a principal object of the invention is to provide improved synthetic lubricant fluids for use as crankcase oils and as lubricants generally, which comprise polypropylene glycol diether as a base fluid and an improved sludge dispersant additive.

A more specific object of the invention is to provide an improved dispersant additive comprising polyalkylene glycol mercaptosuccinimides.

An additional and more specific object of the invention is to provide a lubricating composition including a polyalkylene glycol diether lubricant base fluid in combination with a sludge dispersant additive comprising polyalkylene glycol mercaptosuccinimides.

A further and more specific object of the invention is to provide a class of polyalkylene glycol mercaptosuccinimides for use as lubricant additives. I

A process for preparing lubricant additives and lubricant fluids constitutes an additional and still more specific object if the invention.

The provision of the specific compounds described hereinafter and the specific processes for producing these compounds and the described lubricant fluids constitutes an additional and highly specific, but non-limiting, object of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT The foregoing and additional objects are accomplished in general by preparing the desired polyalkylene glycol mercaptosuccinimide and blending the resultant product with a propylene glycol diether polymer lubricating fluid generally of the type identified as Ucon fluid DLB-200E or equivalent.

The dispersant additives of this invention are prepared, in general, by refluxing mercaptosuccinic acid or mercaptosuccinic anhydride with a polyalkylene glycol, then refluxing the product of the foregoing reaction with an amine, preferably a polyalkylene polyamine, at a temperature sufliciently high to initiate the reaction and remove water. A solvent, such as toluene, xylene, etc., may

be used during the refluxing operations, if desired.

The first step of the reaction, the formation of the polyalkylene glycol derivative of mercaptosuccinic acid is carried out under atmospheric pressure, with or without the addition of solvent, at a temperature of from about 50 C. to about 250 C., and preferably in the range of about C. to 250 C. for from about 1 to about 500 hours, preferably from about 10 to about hours.

The second step of the reaction, the formation of the succinimide by reaction of the polyalkylene glycol derivative of mercaptosuccinic acid with a polyalkylene polyamine is also preferably carried out at atmospheric pressure preferably in the presence of a solvent which is inert to the reaction, such as paraflinic and cycloparaflinic hydrocarbons, benzene, alkylbenzenes, etc., e.g., toluene and xylene. The reaction may be carried out from about 50 C. to about 300 C., preferably in the range of from about 80 C. to 150 C. for reaction times of between about one-half hour and 40 hours, preferably from 1 hour to 8 hours.

The process is illustrated by the following specific embodiment showing the reaction conditions thereof.

0.1 mole of a polypropylene glycol ether identified as Ucon fluid LB-385 (0.1 mole) and mercaptosuccinic acid (0.1 mole) were added to a 500 ml. reaction flask. Ucon LB-385 has an apparent specific gravity at C. of 0.995, a viscosity index (ASTM D-567) of 144, a viscosity, Saybolt seconds at 210 F. of 75, at 100 F. of 385 and at 0 F. of 15,000, a viscosity in centistokes at 210 F. of 14.3, at 100 F. of 83.3, and at 0 F. of 4,700 with a pour point (ASTM D-97) of F. and a fire point (ASTM D-92) of 500 F. The molecular Weight of the polypropylene glycol is about 1500. This fluid is produced by Union Carbide Plastics and Chemicals Department, New York.

The reaction mixture was heated to 100 C. with stirring. The temperature increased to 120 C. with moisture coming off. 100 mls. of benzene was added and the reaction was continued. The temperature continued to increase to about 200 C. as benzene was partially removed (ca. ml.). At this point, the reaction vessel was cooled down to 45 C. and reheated to C. The temperature increased to 96 C. and the reaction was allowed to continue for a total running time of 136 hours.

Tetraethylenepentamine (0.04 mole) and mls. of toluene was added and the reaction mixture was refluxed at C. for 6 hours. Moisture coming off from the reaction mixture was collected as the color of the reactive to used Ucon DLB-20OE obtained from engines used in dynamometer tests. The dispersant additive product of the aforementioned process was mixed with the material to be tested in a Waring Blendor for 5 minutes. The sample was observed for sludge separation and paper chromatographic spot tests were made to determine dispersant effectiveness. Data showing the relative effectiveness of the composition of this invention are given in Table I along with comparative data using other known and experimental dispersant additives.

TABLEEL-DISPERSANT TESTS {Waring Blender, high speed5 minutes] Percent Percent separation after settling- Code number cone. Structure 24 hrs. 240 hrs.

Standard #1 100 Used Ucon from chassis dynamometer test on Chevrolet 19 72 Standard #2.. 100 Used Ucon from chassis dynamometer test on Ford 4 58 640-42-2 5 Mercaptosuecinic acid plus Ucon LB-385 plus tetraethylenepentamine 1 3 CH3\ R\O CHzH S-CHC O N- CHZCHZNH -H and/or ornoo CH HS-CHCOr-CHCHzO R CHzC0(NHCH-. CHz NH2 6493l-6 5 CH3 CH3 4 43 CrzHza-CHC O2HCHz\O HCHZ, O R

5 Tetrapropenylsuceinie anhydride plus triethylenetetramine. 3 a 19 649-31-7 5 CH I OH; b 3 l 3 CIZHZFCHCOZJ-JHCHZTOCHCHZTOR CHZCO NHCHzCH2 NH2 649-214 5 UlzHza-CHC 0 17 I 30 N CHzCHzCHzN HCHzCHzCHzNHz CHzCO 640-14-1 5 CnHzg-(HCO b 6 I 16 NCHzCHZNHCI-I CHZNHI plus (AI-[2C0 C1zH2a-(HCO (JO-CH2 N CHzCHzNHCHzCHzN C/HBCO CO-CH-Cufin 64019-1-...:.3-2.25.1; 6 C zHza-(HCO 3 I 58 NCHzCHgNH CHzGO I Soap-like deposit formed on graduate. b At 72.

The significant advantages of the compositions of this invention compared with other dispersant compounds are immediately apparent. The significantly greater effectiveness as a dispersant additive of the inventive compounds, as compared with structurally similar compounds, is quite unexpected.

While I do not wish to be bound by the following equation, it is believed, on the basis of infrared data, molecular weight, etc., that this equation properly describes the reaction of the process described hereinbefore, however, certain side reactions of undetermined nature are also believed to occur.

wherein n and m are positive integers. In the foregoing process, a polyalkylene glycol wherein n was 25 and a polyalkylene amine wherein m was 4 were used; however, n may be a positive integer from 1 to 100 and m may be a positive integer from 1 to 10. Normally, it should be greater than 10 and, within broad ranges, n. should be at least about 5 times m and preferably from 5 to 15 times m. 'R is a lower alkyl group or hydrogen, preferably methyl.

In addition to being effective as a dispersant additive for lubricants, the compounds of this invention, by reason of the mercapto structure, also serve as anti-wear agents and are effective as corrosion and oxidation inhibitors, thereby reducing the required concentration of specially compounded corrosion and oxidation inhibitors.

The lubricating compositions of this invention are preferably formed by blending the mercaptosuccinimide compounds heretofore described with end-blocked polyalkylene glycol ether lubricating fluids, for example the endblocked polypropylene glycol ether identified as Ucon fluid DLB-200E available from Union Carbide Plastics and Chemicals Department, New York. The dispersant additive concentration level is from 0.1 to percent generally, preferably from about 1 percent to about 5 per cent, by weight. Oxidation inhibitors are also added in the 0.1 percent to 5 percent range, preferably in the range of from 0.5 percent to 3 percent. Many conventional oxidation inhibitors were tested and found to be successful, for example, 3 percent Oronite 254 is the preferred additive but 1 percent concentration of 4,4-methylene, bis-2,6- ditertiary butyl phenol (Ethyl 702), an alkylated phenol (Lubrizol 814), phenyl alpha-naphthylamine, and an alkylated diphenylamine (VanLube SL) were found to be successful oxidation inhibiting additives.

Ucon DLE-200 fluid is amber in color, has a viscosity at 210 F. of 58.3 (SUS), at F. of 201 (SUS) and at 0 F. of 5660 (SUS). The viscosity, in centistokes, is 9.70 at 210 F., 43.2 at 100 F., 1230 at 0 'F., 4140 at 20 RF. and 23,800 at 40 F. The viscosity index is 161, the pour point is 50 F., the flash point is 520 F. and the fire point is 565 F. This product is described in Union Carbide Chemicals Company Advance Technical Information publication F-40400, June 1959. Double endblocked lubricants of this class generally may be used in the compositions of this invention, the primary consideration being the desired viscosity and viscosity index. The manufacture and properties of these compounds is dis cussed by Gunderson and Millet, Synthetic Lubricants, Reinhold, New York, 1962, chapter on Polyglycols. Reference is made to this work and the publications and patents cited therein for a complete discussion of the lubricant base stocks used in the inventive composition.

It is difficult to overestimate the importance of providing the proper blend of lubricating fluid, dispersant additive, and oxidation inhibitor. To illustrate, using the fluids of the present invention, e.g., an end-blocked polyalkylene glycol ether lubricating base fluid, a mercaptosuccinimide dispersant additive of the type described, and an oxidation inhibitor, e.g., Oronite 254, there is provided a potential lifetime motor lubricant. The lubricating properties of the base fluid are not diminished under normal operating conditions; however, over long periods of time the base fluid may be oxidized to form volatile components which are discharged from the crankcase. An effective oxidation inhibitor is, therefore, necessary to prevent too rapid decomposition of the base lubricating fluid resulting in the necessity for continual addition of lubricant. Sludge is formed in every internal combustion engine from combustion products, Wear products, etc. It is essential that this sludge be maintained in the lubricant and carried to an effective filter. Therefore, an effective dispersant additive is required to provide an essentially homogeneous circulating lubricant fluid in which the sludge forming materials are maintained in dispersion. As the homogeneous fluid is circulated through the oil filter, the sludge components are removed and the clean lubricating fluid is returned to the crankcase. Except for occasional addition of lubricating fluid, no additional attention need be given to a vehicles engine lubricating system. The convenience and economy of this type of fluid are immediately apparent.

The lubricating compositions of this invention, the dispersant additives, and the process for preparing these products have been set forth in rather specific terms to aid those skilled in the art to understand and to practice the invention. Departures from the specific disclosure will be made by those skilled in the art based upon the principles and teachings herein and such variations may be made without departing from the spirit and scope of the invention, as defined in the following claims.

I claim:

1. The product of the reaction under reflux conditions of (a) a compound selected from the group consisting of mercaptosuccinic acid and mercaptosuccinic anhydride, (b) a polypropylene glycol having the formula wherein n is a positive integer from 1 to 100 and R is lower alkyl or hydrogen and (c) a polyalkylene polyamine having the formula H2N{CH2CH2NH ;-H wherein m is a positive integer from 1 to 10 with the proviso that n is at least three times the value of m; said polyamine being reacted with the product formed from (a) and (b).

2. The reaction product of claim 1 wherein n is from 5 to 15 times the value of m.

3. The reaction product of claim 1 wherein n is between 5 and 15 times the value of m and R is methyl.

4. The reaction product of claim 1 wherein m is 4 and n is 25.

5. The reaction product of claim 1 wherein said polyalkylene polyamine is tetraethylenepentamine.

6. A process comprising the steps of reacting (a) a compound selected from the group consisting of mercaptosuccinic acid and mercaptosuccinic anhydride with (-b) a polypropylene glycol having the formula CH3 R 0c1i2011 I1 wherein n is a positive integer from 1 to 100 and R is lower alkyl or hydrogen and further reacting the product of (a) and (b) with a polyalkylene polyamine having the formula i wherein m is a positive integer from 1 to 10 with the proviso that n is at least 3 times the value of m, at a temperature of from about C. to about 300 C. for from about /2 hour to about 500 hours.

7. The process of claim 6 wherein the process is carried out in two sequential steps and wherein the temperature of the first step is between about C. and about 250 C. and the time is from about 10 to about hours, and wherein the temperature of the second step is between about 80 C. and about 150 C. and the time is from about 1 hour to about 8 hours.

References Cited UNITED STATES PATENTS 3,390,086 6/1968 OHalloran 260326.5SX

NICHOLAS s. RIZZO, Primary Examiner J. A. NARCAVAGE, Assistant Examiner US. Cl. X.R. 260-481 R 

